Maize is a major food crop in China, and plays an important role in feeding and bioenergy, and now has become the crop with the largest planting area and the highest total yield in China. Heterosis is widely used to substantially improve yield, resistance, and quality of crops. Maize is among the crops of which heterosis has long been utilized. The first maize hybrid emerged in 1924. The main bottleneck for utilizing heterosis of maize is emasculation of the female parent for seed production. There are mainly two modes of emasculation employed in commercial breeding: manual emasculation and mechanical emasculation. However, there are disadvantages for both of the two emasculation modes: manual emasculation is incomplete, subject to the decrease of seed purity, and meanwhile greatly increases the cost, while mechanical emasculation requires specific plant architecutre with sparse upper leaves and large and flat planting plots. However, the maize varieties in China predominantly have compact architecture. In addition, mechanical emasculation is unfeasible in the northwest of China such as Gansu Province, mainly due to the fragmentation of the seed production areas. Meanwhile, in maize hybrid seed production, there exists the problem that the genetic backgrounds of the parental lines commonly used for breeding are not substantially different, and therefore affects the fulfillment of the main breeding objectives such as high yield, stable yield, resistance, early maturity, etc. Male sterility can be used in seed production not only to avoid the problem of seed purity decrease due to the incomplete emasculation of the female parent, but also to replace mechanical emasculation and reduce seed production costs; and the most fundamental step for this technology to be used in seed production lies in obtaining sterile lines with complete and stable sterility and the corresponding restorer lines that can be easily found. Maize cytoplasmic male sterility line is susceptible to leaf spot disease and it is hard to obtain the corresponding restorer line, but the nuclear male sterile line could overcome leaf spot disease and the corresponding restorer line can be easily found. Therefore, it is important to strengthen the research on the maize nuclear male sterile mutants and the controlling genes in hybrid breeding and production of maize.
To solve the problems in the current method for maize hybrid breeding, such as the technology bottlenecks including incomplete manual emasculation, the limited variety resources for hybrid breeding, the complexity in seed production technology, and the high cost of seed production and so on; people are trying a new hybrid breeding technology, in which the new hybrid breeding technology fully utilizes male sterile genes controlled by recessive nuclear genes to construct sterile lines with stable fertility that is not affected by environment. The main technical advantages include: firstly, the step of either manual emasculation or mechanical emasculation is omitted, seeds with higher quality and purity can be supplied to the growers; secondly, the recessive nuclear sterile genes used are applicable to the great majority of varieties, which greatly improves the utilization of the heterosis resources and solves the problem for the utilization of the heterosis resources; thirdly, sterile line reproduction via hybridization is simplified. The present invention provides a maize gene involved in pollen development and a male sterile line produced based on the mutation of the gene, which has stable fertility and is not generally affected by environmental conditions. This gene and the sterile line produced based on the mutation of the gene provide essential elements for constructing a novel hybrid breeding system.